Novel photographic products and processes



BSTRACT on THE DiscLosuRE Polymeric viscosity-increasing agents incorporated in processing compositions ordinarily utilized in diffusion transfer photographic processes have been found, .incertain instances, to inhibit the transfer ofimage-forming.

components from the photosensitive element to there.- ceiving element. The degreeofinhibition is dependent on the' amount of polymer present.inithe'processirig composition and may be substantially reducedby using less polymer and adding a cross-linking agent thereto prior 'to the time it is used in said diffusion transfer process,

thereby maintaining the desired processing composition viscosity.

The present invention is concerned with photography and, more particularly, with diffusion transfer processes.

The present invention is especially related to silver and color diffusion transfer processes of the type wherein a transfer image is obtained in a single step by treating an exposed photosensitive element with a layer of a suitable processing solution to provide,'as a function of development, an imagewise distribution of image-forming components, and transferring at least a portion of the imagewise distribution of image-forming components to a super posed image-receiving element to form a transfer image thereon. I r

In silver diffusion processes, an exposed photosensitive silver halide emulsion is developed and almost concurrently therewith a soluble silver complex is obtained by reaction of a silver halide solvent with the unexposed and undeveloped silver halide of said emulsion. Preferably,

the photosensitive silver halide emulsion is wet with a layer of processing composition which is spread between the photosensitive element comprising the silver halide.

emulsion and an image-receiving element T he processing composition effects development of the latent image in the emulsion and substantially contemporaneous therewith forms a soluble silver complex, for example, a thiosulfate or thiocyanate, with undeveloped silver halide. This soluble silver complex is, at least in part, transferred to the image-receiving element and the silver.

Filed Sept. 20, 19. 5, 'Ser. N ."'4ss,7s21

United States PatentO latent image and color couplers are the color-providing substances, and the processes disclosed in Patent No. 2,774,668, issued Dec. 18, 1956, to Howard G.

Rogers, wherein complete, preformed dyes .are used as the celor-providing substances.

" out such'diffus iontransfer processes, a'layer of the procthereof is largely precipitated thereon to form the trans;

fer image. 7 H

In color diffusion transfer processes, a photosensitive element including a silver halide emulsion layer is exposed to create therein a latent image. The latent image is developed and, concurrent with and. under the control of this development, an imagewise distribution of mobile color-providing substances is formed. At least a portion of the e color-providing substances is transferred to a superposed image-receiving layer to form a colored image thereon. As examples of such processes, mention may be made of the processes disclosed and claimed in US. Patent No. 2,983,606, wherein dye developers (i.e., compounds which contain in thesame molecule both the chromophoric system of a dyeand also a silver halide developing function) are the color-providing substances, the processes disclosed and claimed in US. Patent No. 2,647,049, issued July 28, 1953, to Edwin H. Land, wherein color developers are employed to develop the essingsolution is applied between the photosensitive ele ment anda superposed image-receiving element, and the imagewise, distribution of image-forming components is transferred through the layer of processing solution to the image receiving layer. Inparticularly useful embodiments, the processing solution is dispensed between the photosensitive element and the image-receiving element from 'a rupturable container such as disclosed in US. Patent No. 2,543,181 by moving said container between a pair of pressurear'ollers such as provided in cameras such as. disclosed in lj s, Patents Nos. 2,435,717 and 3,165,039. In especially useful embodiments, the processing solution comprises a polymeric viscosity-increasing reagent to facilitate the spreading of the solution between the photosensitive element and the image-receiving element. Such reagents generally serve to slow down the flow rate of the processing solution so that it can be more uniformly controlled and distributed between the superposed negative and image-receiving element.

Generally, the polymeric viscosity-increasing reagents which are used in the above embodiments are soluble in aqueous alkaline solutions and are inert with respect to the photographic reagents which may be present, e.g., developers, antifoggants, alkali, silver halide solvents, etc. In the past, water-soluble hydroxy-substituted polymers have been found useful. In especially useful embodiments, hydroxyalkyl ethers of cellulose, such as hydroxyethyl cellulose have been employed.

Although the polymeric viscosity-increasing reagents provide beneficial results, it has been found that in certain instances they inhibit the transfer of the imageforming components through the processing solution. Moreover, in color processes such reagents may also have an afiinity for the color-providing substances and necessitate the use of additional amounts of such substances to provide a dense image.

In the present invention it has been found that 1) denser transfer images and (2) a substantial reduction in the amount of polymeric viscosity-increasing compound, necessary to provide the desired mechanical behavior of the processing solution, may be brought about by incorporating a cross-linking agent for said polymeric viscosity-increasing reagent in the processing solution.

One object of the present invention is to provide photographic processing solutions for diffusion transfer processes comprising a polymeric viscosity-increasing compound and a cross-linking agent for said compound.

Another object of the present invention is to provide photographic processing solutions for dye developer diffusion transfer processes, comprising a polymeric viscosityincreasing compound and a cross-linking agent for said compound whereby the density of the transfer image is substantially enhanced.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the process involving the several steps and the relation and order of one or more of such steps with respect to each of the others, and the product possessing the features, properties and the relation of elements which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of Patented July 2, 1968 In the most coinmonly employed method for carrying 3 the invention, reference should be had to the following detailed description.

The present invention has been found particularly useful for increasing the density of dye developer diffusion transfer images such as produced by the process disclosed in the above-mentioned U.S. Patent No. 2,983,606. In such processes an exposed photosensitive silver halide emulsion is developed in the presence of a dye developer. The dye developer in exposed areas is oxidized and immobilized as a function of development to provide an imagewise distribution of mobile, unoxidized dye developer in unexposed areas. The immobilization is apparently due at least in part to a change in solubility characteristics of the dye developer upon being oxidized. At least a portion of the imagewise distribution of mobile unoxidized dye developer in unexposed areas is trans ferred by imbibition to a superposed image-receiving layer to form the transfer image thereon. Multicolor transfer images may be produced by such processes by using photosensitive elements such as those claimed and disclosed in the copending U.S. application of Edwin H. Land and Howard G. Rogers, Ser. No. 565,135, filed Feb. 13, 1956, wherein at least two selectively sensitized photosensitive strata are superposed on a single support and are processed with a single processing solution and transferred to a common image-receiving layer. A suitable arrangement of this type comprises a support carrying a red sensitive silver halide emulsion stratum, a green-sensitive silver halide emulsion stratum, and a blue-sensitive silver halide emulsion stratum, said emulsions having associated therewith, respectively, a cyan dye developer, a magenta dye developer, and a yellow dye developer. In preferred embodiments the dye developers are disposed in separate alkali-permeable layers behind the silver halide emulsion with which they are associated.

Generally, the cross-linking agents employed in the present invention will vary depending on the nature of the polymeric viscosity-increasing agent. Cross-linking agents for the various types of polymers which can be used for this purpose are well known. In general, such cross-linking agents comprise at least two functional groups within the molecule which will react with functional groups on the polymeric chains and bond the chains to one another. It is preferable that the resulting bond be one which will be resistant to alkali. Especially useful cross-linking agents for hydroxy-substituted viscosity-increasing polymers are those which form an ether bond. As examples of useful crossdinking agents, mention may be made of the di-epoxides such as butadiene di-epoxide and 1,3-butane diol diglycidyl ether; dihalides such as 2,3- dichlorodioxane; and divinyl sulfone. 1,3-outane diol diglycidyl other has been found particularly useful.

The present invention is particularly useful with alkalisoluble hydroxy-substituted polymers such as the hydroxyalkyl celluloses mentioned above. As examples of other hydroxy-substituted polymers, mention may be made of polyvinyl alcohol, partial acetals of polyvinyl alcohol, copolymers of vinyl alcohol, hydroxymethyl cellulose, cellulose, hydroxyethyl polyvinyl alcohol, etc.

The amount of cross-linking agent employed in the processing solution may be varied over a considerable range. Usually the minimum will not be critical and can be varied depending upon the degree of improvement desired. Generally, an effective amount will be that which Will bring about an increase in the molecular weight of the polymeric viscosity-increasing compound. The maximum amount of cross-linking agent on the other hand is considerably more critical and should be limited so as not to reach the gelation point of the processing solution, i.e., the point at which the processing solution becomes a solid (infinite viscosity) and cannot be reverted to a viscous liquid by simple shear forces such as would be encountered in spreading the processing solution or dispersing it from a rupturable container between a pair of rollers, such as pointed out above, e.g. shear forces of about 5,000 to 40,000 dynes/cm Generally the maximum amount will vary with the nature and molecular weight of the polymeric viscosity-increasing compound and can be readily determined by adding varying amounts to samples of the processing solution and selecting the one with the desired consistency. As can be understood, a greater quantity of cross-linking agent would be required for a relatively low molecular weight polymer than would be necessary for a higher molecular weight polymer. It has been found useful that the processing solutions have apparent viscosities of at least 100,000 centipoises and more particularly at least 200,000 centipoises, as measured by a Brookfield Viscosimeter, Model LVT, using a No. 4 spindle at 0.3 r.p.m. and a temperature of 25 C. In especially useful embodiments of the present invention sufficient cross-linking agent is employed so as to reach the incipient gel point of the processing solution, i.e., the point at which the solution is on the border line betveen a sol and a gel. A preferred system of the present invention is hydroxyethyl cellulose crosslinked with about 5 to 20% 1,3-butane diol diglycidyl ether by weight of the polymer. It should be understood that a portion of the cross-linking agent is rendered inactive in the alkaline solution in which it is used and does not take part in the cross-linking reaction.

In a preferred mode of preparing the processing solutions of the present invention, the polymeric material is first dissolved in the alkaline solution and then reacted with the cross-linking agent. Subsequent to the crosslinking action the other desired photographic agents are added. As examples of photographic reagents which may be present, mention may be made of dye developers; silver halide developing agents, such as l-phenyl-3-pyrazolidone, phenyl hydroquinone, and toluhydroquinone; silver halide solvents, such as sodium thiosulfate or sodium thiocyanate; alkalies, such as potassium hydroxide and cesium hydroxide; antifoggants, such as benzotriazole; and quaternary ammonium compounds, such as N-phenethyl- Ot-PlCOlilliUl'l'l bromide and N-benzyl-ot-picolinium bromide.

The novel processing compositions of this invention were tested in dye developer color diffusion transfer processes on multilayer photosensitive elements prepared in a manner similar to that disclosed in the above-mentioned U.S. Patent No. 2,983,606 and in the copending application of Edwin H. Land and Howard G. Rogers, Ser. No. 565,135, filed Feb. 13, 1956. In general, the photosensitive elements comprised a support carrying a red-sensitive silver halide emulsion stratum, a green-sensitive silver halide emulsion stratum, and a blue-sensitive silver halide emulsion stratum; said emulsions having dispersed in separate gelatin layers behind them, respectively, a cyan dye developer, a magenta dye developer and a yellow dye developer, each pair of emulsion and dye developer layers being separated by an interlayer. The particular dye developers employed in the photosensitive elements were (1) 1,4 -bis-[ot-methyl ,8-(a,5'-dihydroxyphenyl)- ethylamino]- anthraquinone (a cyan dye developer), (2) 2-[p-(2,5'-dihydroxyphenethyl) phenylazo] 4 isopropoxy-l-naphthol (a magenta dye developer), and (3) l phenyl 3 N-n-hexyl-carbamyll-[p-hydroquinonylethyl)-phenylazo]-5-pyrazolone (a yellow dye developer).

The image-receiving element used in testing the compositions of the present invention was prepared in a manner similar to that disclosed in the copending applications of Howard C. Haas, Ser. No. 50,848, filed Aug. 22, 1960, and Edwin H. Land, Ser. No. 234,864, filed Nov. 1, 1962, and comprised an image-receiving layer containing polyvinyl alcohol and poly-4-vinylpyridine, an underlying polymeric acid layer, and a support.

The following aqueous processing compositions are illustrative of the present invention. An aqueous processing composition designated Control, exhibiting approximately the sarne viscosity or spreading behavior as Compositions 1 and 2, is presented herewith for purposes of comparison.

Composition No. 1

N-benzyla-pico1inium bromide Sodium thiosulfate Composition No. 2

Potassium hydroxide 11.2 Hydroxyethyl cellulose 1 2.0 Epichlorohydrin 0.1 Benzotriazole 2.3 N-benzyl-a-picolinium bromide 2.3 Sodium thiosulfate 115 Control Potassium hydroxide 11.2 Hydroxyethyl cellulose 3.75 Benzotriazole 2.3 N-benzyl-u-picolinium bromide Sodium thiosulfate High viscosity hydroxyethyl cellulose sold by Hercules Powder Co. Wilmington, Del., under the trade name Natrosol 250 Type 1%."

In conducting the tests, areas of photosensitive elements were exposed to (1) blue and green light only, (2) red and blue light only, (3) red and green light only, (4) totally exposed, and (5) unexposed. The photosensitive elements were processed for 35 seconds at 106 F.,' 50 seconds at 72" F., and 90 seconds at 38 F. The integral densities in the various areas of the image-receiving elements, appearing in tabular form below, were measured by reflectance using red, green and blue filters.

carried out with the novel processing composition of the present invention. Moreover the spreading characteristicsv of the compositions of the present invention were substantially the same as the control which contained considerably more of the hydroxyethyl cellulose.

Another factor in overall image quality that should be noted is that, while there is a net increase in the density of all dyes, the greatest increase occurs in the dyesin which an increase was considered desirable. Therefore, it has been found unnecessary to readjust the dye ratios in the negatives.

It has also been noted that high quality dye images can be obtained on image-receiving elements that are separated by a wider gap range than has been heretofore possible.

It was further found that the above processing solutions of the present invention were less temperature sensitive and were less adherent to the image-receiving element.

The novel processing compositions of the present invention may also be used in conventional developm nt processes, black-and-white, as well as color.

Since certain changes may be made in the above product and process without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description,-shall be interpreted as illustrative and not in a limiting sense.

What is claimed is.

1. The use in photographic'processes of a processing solution comprising a polymeric viscosity-increasing compound and a cross-linking agent for said polymeric compound, the amount of said cross-linking agent being insufiicient to cause gelation of said polymeric compound, wherein said polymeric compound is an alkali-soluble TRANSFER DENSITIES Processing Temp, 106 F.

Processing Temp., 72 F.

Exposure Red Green Blue Red Green Blue Red Green Blue Filter Filter Filter Filter Filter Filter Filter Filter Filter Control:

Blue and Green 0. 96 0. 38 0. 34 0.84 0. 34 0.32 0.50 0.28 0. 38 Red and Blue.'. 0. 11 0.86 0.55 0. ll 0. 80 0. 52 0. 13 0.56 0.45 Red and Green.-- 0. 05 0. 19 0. 88 0. 05 0. 21 0.91 0. 08 0. 26 l. 07 Total Exposure. 0. 05 0. 09 0. 13 0. 04 0. 08 0. 11 0. 04 0. 1O 0. 22 No Exposure 1. 15 1. 46 1. 62 0.98 1. 44 1. 75 1. 04 1. 27 1. 96 Composition No. 1: 7

Blue and Green 0. 98 0. 39 0. 34 1. 19 O. 46 0. 42 0.62 0. 34 0.49 Red and Blue 0. 11 0.95 0. 59 0. 14 0. 98 0. 62 0. 15 O. 69 0. 57 Red and Green- 0. 05 0. 22 0. 97 0. 06 0. 24 1. 04 0. 08 0. 28 l. 09 Total Exposure. 0. 04 0. 0. 16 0. 04 0. 10 0. 0. 06 0. l4 0. 29 No Exposure 1. '1. 78 1. 94 1. 38 1. 93 2. 09 1.09 1. 62 2. 22 Composition No. 2:

Blue and Green... 1. 26 0. 48 0. 42 l. 08 0. 46 0. 43 0. 69 0. 38 0. 50 Red and Blue... 0. 15 0. 94 0. 61 0. 14 0.96 0 61 0. 14 0.60 0. 53 Red and Green- 0.07 0.22 0.95 0. 07 0.24 1. 02 0. 10 0. 29 1. 18 Total Exposure. 0.08 0. 12 0. 16 0.05 0. 10 0. 15 0.06 0. 14 0. 28 No Exposure.... 1. 44 l. 78 1. 92 1. 40 1.94 2.14 1. 68 1. 84 2. 53

Composition No. 3

A composition was made up in a manner similar to example Composition Nos. 1 and 2, except that 0.3% of 1,3-butane diol diglycidyl ether was used in place of the epichlorohydrin. When the composition was tested in a manner similar to Composition Nos. 1 and 2 at 75 F., it showed the following results:

TRANSFER DENSITIES Exposure Red Filter Green Filter Blue Filter Processing Temp., 75 F.

Blue and Green. 1. 29 0. 49 0. 48 Red and Blue.-- 0.13 0.92 0.63 Red and G1 een.- 0.05 0. 25 1.16 Total Exposure.. 0. 03 0.08 0.16 No Exposure 1. 43 1. 83 2. 20

hydroxy-substituted polymer and said cross-linking agent torrns ether bonds with said polymer.

2. The invention as defined in claim 1 wherein sufiicient cross-linking agent is present to reach the incipient gelation point.

3. The invention hydroxy-substituted 4. The invention cross-linking agent epichlorohydrin.

5. The invention as defined in claim 3 wherein the cross-linking agent for hydroxyethyl cellulose is 1,3- butane diol diglycidyl ether.

6. In a difiusion transfer photographic process Wherein an exposed photosensitive element is treated with a layer of photographic processing solution to provide an imagewise distribution of image-forming components at least a portion of which are transferred through said layer of photographic processing solution to a superposed image-receiving layer to form a transfer image thereon, the improvement wherein said processing solution comprises a polymeric viscosity-increasing compound and a cross-linking agent for said compound,

as defined in claim 1 wherein said polymer is hydroxyethyl cellulose. as defined in claim 3 wherein the for said hydroxyethyl cellulose is the amount of said cross-linking agent being insufficient to cause gelation of said polymeric compound.

7. The invention as defined in claim 6 wherein said image-forming components aredye developers.

8. The invention as defined in claim 6 wherein sufiicient cross-linking agent is present to cause said polymeric compound to reach its incipient gelation point.

9. The invention as defined in claim 6 wherein said polymeric viscosity-increasing compound is an alkalisoluble hydroxy-substituted polymer.

10. The invention as defined in claim 9 wherein the cross-linking agent for said polymeric viscosity-increasing compound forms ether bonds with said hydroXy-substituted polymer.

11. The invention as defined in claim 9 wherein said hydroxy-substituted polymer is hydroxyethyl cellulose.

5 cross-linking agent for said hydroxyethyl cellulose is 1,3-

butane diol diglycidyl ether.

References Cited UNITED STATES PATENTS 10 2,662,822 12/1953 Land 9629X 2,968,554 1/1961 Land 963 NORMAN G. TORCHIN, Primary Examiner.

J. P. BRAMMER, Assistant Examiner. 

